7 Pin Towing Questions

[ramangain]

Yup tell me about it... Now time to find the pictured box above since it is OEM wiring and not some shop job. Just seems odd that I would get voltage to only one blinker (right) but not other and then no tail lights?!

Is there a relay associated with the towing box in one of the kick panels? Looking through my EWD and FSM last night I could find nothing on towing harness or any sort of harness in that area.

How about actual brake lights? I had similar symptoms at first.

When I first tested my original 4 pin flat, all I got was brake lights and the right turn signal. At first, I tried just to clean the 4 pin connector by digging out the years of oxidation and environmental crap which had contaminated the plug. I got the left turn signal to work, but still no tail lights. After a couple of hauls with it like that with the original 4 pin, the left turn signal stopped working again. At that point I installed that product I post about (4 pin to 4 pin + 7 pin) and originally just did the original truck 4 pin output to the input 4 pin on the adapter. I had brake, right turn, and intermittent left turn and tail lights. Rather than chain smoke two packs of cancer sticks and stew in my frustration and anger, I just lopped off the 4 pin input adapter and output 4 pin from the truck and hardwired those 4 wires together, AND cleaned the pin receptacles for the OEM plug near the rear silencer, and voila, all was fixed.

Then I started to chase down wiring quirks on my 16x8 trailer. That would qualify as a build thread in an appropriate forum.

Hang in there!

 

[gregnash]

How about actual brake lights? I had similar symptoms at first.

When I first tested my original 4 pin flat, all I got was brake lights and the right turn signal. At first, I tried just to clean the 4 pin connector by digging out the years of oxidation and environmental crap which had contaminated the plug. I got the left turn signal to work, but still no tail lights. After a couple of hauls with it like that with the original 4 pin, the left turn signal stopped working again. At that point I installed that product I post about (4 pin to 4 pin + 7 pin) and originally just did the original truck 4 pin output to the input 4 pin on the adapter. I had brake, right turn, and intermittent left turn and tail lights. Rather than chain smoke two packs of cancer sticks and stew in my frustration and anger, I just lopped off the 4 pin input adapter and output 4 pin from the truck and hardwired those 4 wires together, AND cleaned the pin receptacles for the OEM plug near the rear silencer, and voila, all was fixed.

Then I started to chase down wiring quirks on my 16x8 trailer. That would qualify as a build thread in an appropriate forum.

Hang in there!

Yeah when testing I got nothing other than the one turn signal. Even when guy hooked up the trailer to the truck he got nothing. Exact same guy, trailer and wire extension on the 4Runner resulted in everything working.
I did probe wires right after the stock plug and got nothing other than one turn signal. Did same closer to where wires enter body on quarter panel and same thing. So based on that I am thinking that it is the controller or it is the wiring somewhere else down the line.

 

[gregnash]

Well got it figured out I believe, need to find a trailer to test it out. Looks like the 4-pin plug was the issue. Found the tow box and tested at the box connector and all was good.
Then I tested a after the connector in the quarter panel before it exits the body.
all was good.
Then tested again, actually cutting into the wire near the plug and everything was good. So I said screw it and cut the plug off, wired everything together on the new Hopkins 4+7-pin and seems to be good. Still need to wire up the reverse lights and the aux power.

 

[ramangain]

BAM!!!

 

[gregnash]

Well s***... partial victory. Brakes work, Turn signals work but running lights don't?????
Guess I gotta go back in and see what's going on. Luckily a neighbor has a 7 to 4-pin adapter thingy that has lights on it. Plugged that into my 7 pin and was able to get this far. Need to go for a ride to blow off some steam so this will be looked at a later date.

 

[ramangain]

Recheck with a multimeter. Did you route all of the wires behind the bendy bar in the back so nothing gets pinched when the spare is back in its place?

BTW I went back and put loom protector or electrical tape on EVERYTHING back there too, along with liberal use of zip ties to get rid of wire slack. Life would hella suck if road or trail debris gets in those wires and yanks them around causing issues.

 

[gregnash]

Recheck with a multimeter. Did you route all of the wires behind the bendy bar in the back so nothing gets pinched when the spare is back in its place?

BTW I went back and put loom protector or electrical tape on EVERYTHING back there too, along with liberal use of zip ties to get rid of wire slack. Life would hella suck if road or trail debris gets in those wires and yanks them around causing issues.

Yeah I am going to have to go back through and check everything to see where the fault is. I could have sworn that I tested at the gray connector but could be wrong. Everything has been loomed that is new and not in original loom. All stuff has been ziptied out of the way for the time being and no crimping on contact with tire. So we shall see once I get a chance to look at everything again.

 

[gregnash]

So went through tonight and routed a new line for the running lights. Without the tow module plugged in the running lights work but once in plug it in (grey module) I lose the running lights. All other options work when the module is plugged in. I checked for continuity and have it so all I can think is there is some weirdness going on in the module.
Wondering if I bypass the module and do new leads from module before the plug if I will run into the same issue. Not a ground issue from what I can tell but not 100% on that.

 

[ramangain]

If I understand correctly, a simple running lights bypass wire around the infamous grey box will solve the issue? If you REALLY want to do it professionally, wire the bypass as the trigger for a relay for the running lights power.

Have you tried the Jeremy Clarkson method on the gray box (light hammer usage)?

 

[Nightbrew]

So went through tonight and routed a new line for the running lights. Without the tow module plugged in the running lights work but once in plug it in (grey module) I lose the running lights. All other options work when the module is plugged in. I checked for continuity and have it so all I can think is there is some weirdness going on in the module.
Wondering if I bypass the module and do new leads from module before the plug if I will run into the same issue. Not a ground issue from what I can tell but not 100% on that.

A few years ago I was having trouble with the module piece in my lx450. I know they are not the same but i sure they are quite similar. I would test, and test but couldn’t figure it out. The issue presented itself in this fashion. If a trailer was not connected, everything tested great at the 4 pin on the vehicle. But once you plugged a trailer into it, not all the lights would work. At this time I can’t recall exactly what did and didn’t work. But the best I could tell it was a slight increase in demand on the module made it malfunction. And I say slight as my test this for this was my utility trailer, that only has 2 led turn/tail/brake combo lights.

 

[gregnash]

If I understand correctly, a simple running lights bypass wire around the infamous grey box will solve the issue? If you REALLY want to do it professionally, wire the bypass as the trigger for a relay for the running lights power.

Have you tried the Jeremy Clarkson method on the gray box (light hammer usage)?

That is what I am wondering... Like I said, if I disconnect the grey plug (waterproof connector that routes to the tow harness 4-pin) and then splice in a line from the taillights to the harness, I get power when the taillights turn on. Keep the splice connected (it is cut near 4-pin) and plug gray connector in and I suddenly lose the taillights at the plug, only getting like .8v. Almost like something is shorting that line out when the connector is plugged into the module.

 

[ramangain]

0.8v sounds like a blocking diode internal to the grey box. If you splice into the brown wire (tails) with an external wire, you may need to snip the brown wire back to the grey box.

Pics would help, don't worry about workmanship during troubleshooting. You can pretty it up and make it weatherproof once it is working.